About the Map

Nutrient Overload from Manure Plus Commercial Fertilizer

• EWG used computer modeling to simulate which fields get manure from the 1,901 animal feeding operations in nine counties in Wisconsin. Orange shows all fields modeled to receive manure between 2014 and 2019. Beige signifies crop fields available to receive manure between 2014 and 2019.
• Three different scenarios were run to allocate manure, as described by:
  • No application to alfalfa: Manure applied to fields to meet the amount of nitrogen recommended for growing crops, including corn, wheat, potatoes or small grains.
  • With application to alfalfa: Manure applied to fields to meet the amount of nitrogen recommended for growing crops. Alfalfa is included as a potential spreading area for manure despite having no nitrogen fertilizer recommendation.
  • Phosphorus application: Manure applied to fields to not exceed the average amount of phosphorus (P205) removed by growing crops. Phosphorus removal was modeled for corn, soybeans, wheat, small grains, potatoes and alfalfa.
• Click on a county to see details, including county name, total number of feedlots (permitted and non-permitted), and animal type responsible for the most manure production. Bar charts show how much Nitrogen and Phosphorus applied in manure and sold in commercial fertilizer meets or exceeds the amount recommended for crops (for Nitrogen) or the amount removed by crops (for Phosphorus).
• Overloading fields with more than the recommended amount of nitrogen seriously increases the risk of polluting drinking water with nitrate, a form of nitrogen associated with increased risk of cancer.
• Overloading fields with more than the recommended amount of phosphorus increases the risk of runoff to surface lakes and rivers, contributing to harmful algae blooms that can cause serious health risks to humans and animals.

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